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<TITLE>dtcollect</TITLE>
<H1>dtcollect on-line help</H1>
<HR>
<P>On-line help in <B>dtcollect</B> is provided by HyperText Markup Language
files that are viewable via a HTML viewer such as NCSA mosaic.
Help is available by choosing <B>Help</B> in the <B>dtcollect</B> menubar.

With <B>dtcollect</B> you can:
<UL>
<LI>  Open and close the X-ray shutter,
<LI>  Move the crystal goniometer to any allowed position,
<LI>  Move the detector goniometer (if motorized) to any allowed position,
<LI>  Move the source to any allowed wavelength (if motorized),
<LI>  Collect single or multiple exposures with and without opening the shutter and with or without 
moving the crystal goniometer: shutter-closed stills (dark images), shutter-open stills,  
shutter-open scans, or shutter-closed scans.  For scans, the crystal can be rotated 
around either of two crystal goniometer axes that are usually called omega and phi;
<LI>  Edit, save, and load scans and/or tables of scans,
<LI>  Collect one scan or a series of up to 100 scans.
<LI>  Monitor the progress of the experiment through nearly instantaneous feedback on the 
current status of the hardware devices: shutter, goniometers, counters, and detectors.
<LI>  Communicate with <b>dtdisplay</b> to automatically display images.
</UL>

<h3>What is a SCAN?</h3>

As used through the d*TREK documentation a scan is a contiguous set (in time and often in 
rotation angle) of collected images.  For example, the first image in a scan might be 
acquired by exposing a crystal for 10 seconds while rotating the phi axis from 0 to 1 
degree, the second image by rotating the phi axis from 1 to 2 degrees, and the last image 
by rotating phi from 179 to 180 degrees.  Or a scan might consist of 100 dark or shutter-closed 
images without moving any motors as a way to characterize the dark current in a 
CCD (charge-coupled device) detector. 

<H3>For more help, choose one of the following topics:</H3>
<UL>
<LI><A HREF=Background.html>Background</A>
<LI><A HREF=MainW.html>Main window commands</A> 
<LI><A HREF=MainWMenu.html>Menu commands</A> 
<LI><A HREF=ScanHelpHTML.html>Scan table dialog</A>
<LI><A HREF=Example.html>Example</A> of <b>dtcollect</b> main window
</UL>

<P>Hyperlinks are usually underlined and displayed in blue letters.

<P>To close a Help window, choose <B>File->Close</B> or
<B>File->Exit</B> from the menubar in this window.

